[ADMIN] 17:55:06 C:\> cd .\vagrant-test
[ADMIN] 17:55:08 C:\vagrant-test> ls
[ADMIN] 17:55:08 C:\vagrant-test> vagrant init debian-wheezy
A `Vagrantfile` has been placed in this directory. You are now
ready to `vagrant up` your first virtual environment! Please read
the comments in the Vagrantfile as well as documentation on
`vagrantup.com` for more information on using Vagrant.
[ADMIN] 17:55:19 C:\vagrant-test> vagrant up --provider=hyperv
Bringing machine 'default' up with 'hyperv' provider...
==> default: Verifying Hyper-V is enabled...
==> default: Importing a Hyper-V instance
default: Cloning virtual hard drive...
default: Creating and registering the VM...
default: Successfully imported a VM with name: DebianWheezy74Base
==> default: Starting the machine...
==> default: Waiting for the machine to report its IP address...
default: Timeout: 120 seconds
Hyper-V failed to determine your machine's IP address within the
configured timeout. Please verify the machine properly booted and
the network works. To do this, open the Hyper-V manager, find your
virtual machine, and connect to it.
The most common cause for this error is that the running virtual
machine doesn't have the latest Hyper-V integration drivers. Please
research for your operating system how to install these in order
for the VM to properly communicate its IP address to Hyper-V.
[ADMIN] 17:57:55 C:\vagrant-test>

I've tried the same thing with an internal switch.

That's fair enough, because the way the hyper-v provider tries to find the IP address is via a powershell command like this:

So it can't determine what IP address was actually assigned to the VM. Yes, the VM does actually get an IP very quickly via DHCP.

There are a number of things that point to needing to upgrade the hyper-v integration services on the VM, but hyper-v doesn't "officially" support debian, just RHEL. The downloads Microsoft supplies simply include rpms. Debian should already have the proper hyper-v goodness. I see that the hyper-v modules are loaded:

I'll mark this as the answer. I haven't tried it, and I have long since abandoned trying to get debian+hyper-v+vagrant to work together. (Instead of using vagrant I spin up and configure the VMs myself, which is not that much work.)
–
jackbJul 11 '14 at 16:46

I imagine that my issue is related to what curriegrad2004 describes here. What version of Windows are you running? I'm on Windows 8.1, which I suspect hits this exact bug, since the kernel in Debian is relatively old.
–
jackbJul 14 '14 at 21:00

Confirmed - upgrading my kernel to 3.14 and using this does work.
–
jackbJul 14 '14 at 21:40